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Bpk 205 > Lec 16/17 > Flashcards

Lec 16/17 Flashcards

1
Q

Function of each lobe

A

Frontal: skeletal muscle movements
Parietal: somatic sensory cortex
Occipital: vision
Temporal: hearing

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2
Q

Primary motor cortex contain

A

Cell body of upper motor neurons

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3
Q

Upper motor neurons are part of

A

CNS

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4
Q

Axons of upper motor neurons will synapse in

A

Grey matter

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5
Q

Lower motor neurons are

A

PNS
Project to innervate skeletal muscle

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6
Q

Peripheral pathway consist of — lower motor neuron

A

1

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7
Q

Axon collateral of lower motor neuron will

A

Branch out at distal end and each collateral will synapse (neuromuscular junction) with 1 muscle fiber

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8
Q

Neuromuscular junction consist

A

Axon terminal
Motor end plate on muscle membrane
Schwann cell sheaths

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9
Q

Schwann cell function at NMJ

A

Secrete chemicals required for formation and maintenance of NMJ

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10
Q

Motor end plate

A

Specialized region of muscle membrane that contain high concentration of nicotinic ACH receptors

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11
Q

Lower motor neuron will release neurotransmitters (ACH) and

A

Muscle cell has NACHR
ACH is always excitatory

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12
Q

Nicotinic ACH receptor

A

Non selective cation channel

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13
Q

NACHR is non selective channel however

A

Na flow/flux is higher
In result cell will depolarize

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14
Q

ACH in NMJ is always

A

Excitatory

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15
Q

Muscle cell name

A

Muscle fiber

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16
Q

Cell membrane of muscle

A

Sarcolemma

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17
Q

Muscle cell cytoplasm

A

Sarcoplasm

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18
Q

Modified ER

A

Sarcoplasmic reticulum

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19
Q

Muscle fascicle

A

Bundle of fibers

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20
Q

Skeletal muscle

A

Bundle of muscle fascicle

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21
Q

Epimysium

A

Connective tissue around skeletal muscle

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22
Q

Perimysium

A

Connective tissue around muscle fascicle

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23
Q

Endomysium

A

Connective tissue around muscle fiber

24
Q

T-tubules

A

T-tubules are extensions of cell membrane (sarcolemma) that associate with ends of Sarcoplasmic reticulum

25
Proteins within myofibril
Myosin Actin Troponin Tropomyosin Titin Nebulin
26
Sarcomere
Unit of myofibril between 2 z-disks
27
Skeletal muscles contain
Organized sarcomeres Striped or striated Like cardiac muscle
28
Striation of skeletal muscle is
Alternation between A band and I band
29
Myosin
Thick filament Motor unit create movement 2 intertwined protein chains Each myosin one actin binding site/one ATP binding site(ATP hydrolyses)
30
Thick filament= —— myosin molecules
250
31
Actin molecule
One actin=Globular g-actin Polymerize to form F-actin Each G-actin single myosin binding site
32
Thin filaments
Two chains of F-actin intertwined
33
Troponin
Trimeric protein Bind to tropomyosin has 2 cCa binding site
34
Tropomyosin
Long protein dimer attach to actin Covering the myosin binding site — so myosin cannot securely attach
35
Titin
Huge, elastic, resting length One Z disk to neighboring M line Return stretched muscle to resting length
36
Nebulin
Along thin filaments Attach z disk but does not reach M line — **inelastic molecule** Structural support for thin filament
37
Molecules required for cross-bridge
Ca ion—enable myosin heads to attach actin by revealing myosin binding site **high-force cross-bridge formation** ATP—bind to myosin and allow it to detach from actin **cross-bridge cycling**
38
Without Ca
-Troponin is inactive -Tropomyosin partially block myosin -Myosin can bind to actin only weakly -Low-force cross-bridge
39
By increase in [Ca]
-activate troponin -pulls tropomyosin away from myosin binding site -myosin bind strongly to actin/complete power stroke -actin filament moves
40
Contraction cycle
1- ATP bind to myosin/myosin release actin 2- Myosin hydrolyze ATP 3- Energy from ATP will rotate myosin head 4- Power stroke happen (tropomyosin moves away) 5- myosin release ADP at the end of power stroke
41
What doesn’t change length
Thick and thin filament A band
42
What change length during contraction
I band H zone Sarcomere shorten (z line closer)
43
Excitation-Contraction coupling in skeletal muscle
1- somatic motor neurons release ACh at NMJ 2- net entry of Na from ACH-receptor-channels 3- AP 4- ap move in t-tubule 5- alter conformation DHP receptor 6- DHP open RyR channels in Sarcoplasmic reticulum which are mechanically gated 7- Ca enter cytoplasm 8- Ca bind to troponin 9- allow actin-myosin binding 10- myosin head execute power stroke 11- actin filament move toward centre of sarcomere
44
Skeletal muscle relaxation (Ca removal)
1- sarcoplasmic Ca-ATPase (SERCA) pumps Ca back into SR 2- decrease free cytosolic Ca 3- Ca unbind with troponin 4- tropomyosin recovers binding site 5- myosin head release 6- titin pull filaments back to their relaxed position
45
Muscle twitch
One contraction + one relaxation In a single fiber
46
Forces in skeletal muscle can
Sum
47
Summation can lead to
1- unfused tetanus 2- complete tetanus
48
Unfused tetanus
Allow muscle to relax slightly between stimuli
49
Complete tetanus
Steady tension No break Full capacity
50
Motor unit
One motor neuron and the muscle fiber it innervate
51
Size of motor neuron related to
Need of refined movement
52
More refined movement’
Fewer fibers per motor unit
53
Order the motor units recruited is related to
Power needed to generate movement — smaller motor unit recruited first
54
Smaller motor neuron
Lower threshold for activation Activate by lower frequency of stimulation from CNS
55
Sarcomers contract with maximum force when ———
They are in their normal resting length prior to contraction — optimal number of cross-bridges

Bpk 205 (30 decks)

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